Electric field at a place is $\overrightarrow {E\,}  = {E_0}\hat i\,V/m$ . A particle of charge $+q_0$  moves from point $A$ to $B$ along a circular path find work done in this motion by electric field 

Three charges $-q, Q$ and $-q$ are placed respectively at equal distances on a straight line. If the potential energy of the system of three charges is zero, then what is the ratio of $Q: q$ ?

A block of mass $m$ moving with speed $v$ compresses a spring through distance $x$ before its speed is halved. What is the value of spring constant ?

A charge $( - q)$ and another charge $( + Q)$ are kept at two points $A$ and $B$ respectively. Keeping the charge $( + Q)$ fixed at $B$, the charge $( - q)$ at $A$ is moved to another point $C$ such that $ABC$ forms an equilateral triangle of side $l$. The net work done in moving the charge $( - q)$ is

State which of the following is correct

When a positive $q$ charge is taken from lower potential to a higher potential point, then its potential energy will